Who’s there? A joke contest

So, I claimed a few days ago that environmentalism is never funny. Apparently, there’s some dispute about this matter. So we’re going to settle it once and for all. And we’re going to start with the most basic unit of humor on the planet, the unit of humor that dragged itself up out of the primordial swamp and flopped onto land, causing the other protozoa to giggle and roll their eyes.

Yes: the knock-knock joke.

You think environmental matters can be funny? Prove it. Leave us a green knock-knock joke in the comments. We dare you.

We’ll select a winner — or maybe let you vote on one — in a week or two. And the winner … oh, the winner. Such fame will come upon them! Such fortune! Such rewards and riches! We can’t even tell you. Cause we don’t know yet.

Rules: it’s got to be about something environmental. Energy, forests, pollution, conservation, you name it. I suppose you can joke about environmentalists themselves, but that’s kind of cheating, since there are few species more mockable.